Kourtney was with her younger sister, 20-year-old Kendall Jenner, who also stunned on the sisters' night out. The model showed off her super tiny waist in a cropped sweatshirt and black trousers, sporting snakeskin-print heels.

Photo: Photographer Group/Splash News

A source tells ET the girls’ night out was actually for Cody Simpson’s 19th birthday. “They were there for a little over an hour,” the source says, noting everyone seemed “pretty relaxed.” “Kourtney had some cocktails, while the other girls did not. They did order a few lite bites though.”

Kourtney's certainly been on a roll lately with her super stylish looks, including this silver strapless Julien Macdonald dress she wore to the InStyle and Warner Bros. Golden Globes after-party on Sunday night. Her date to the big bash was her younger sister, 18-year-old Kylie Jenner, who went for a more dramatic look in a sparkly La Bourjoisie crop top and matching skirt.

"Kourtney is 100 percent over Scott [Disick]," the source revealed. "Not in a hateful way at all, but she has completely moved on."

"This breakup has really showed her that she needs to focus on herself," the source added. "She's spending a lot of time with her girlfriends, is planning dinners and nights out. She's happy and glowing."